考虑土体小应变刚度特征时隧道开挖与周边地下设施相互作用的研究

项目名称： 考虑土体小应变刚度特征时隧道开挖与周边地下设施相互作用的研究

项目编号： No.50808109

项目类型： 青年科学基金项目

立项/批准年度： 2009

项目学科： 金属学与金属工艺

项目作者： 徐明

作者单位： 清华大学

项目金额： 21万元

中文摘要： 本项研究首先系统地整理和分析了关于土体小应变刚度特征的最新研究成果，在此基础之上提出了一种实用的弹塑性本构模型，该模型能够考虑土体在加载和卸载条件下不同的非线性刚度特征，能够较好表达土体在整个应变区间内，特别是小应变区间内的高度非线性特性。同时，对暗挖隧道的超前支护提出了一个简化的均一化横观各向同性弹性模型，并对盾构隧道掘进的三维数值模拟技术进行了探讨。 在上述研究的基础上, 分析了浅埋暗挖法施工地铁隧道时周围土体的变形特点，对比了不同导洞开挖顺序时的土体变形差别，并分析了超前支护施工长度和开挖步距的三维效应；深入研究了当隧道与邻近单桩基础之间相对位置不同时，隧道开挖对桩的影响及其规律，并与已有的现场监测及模型实验结果进行了对比，同时对其机理进行了探讨；系统地分析了隧道开挖对邻近管线的影响,调查了管线刚度和埋深、地层损失率、土体刚度及隧道埋深等主要因素对管线最大弯矩的影响，并对相关规律进行了总结，提出了一种工程上较为实用的管线内力简化计算方法；分析了超大直径盾构在砂土地层中的开挖面稳定性，揭示了考虑由泥水容重导致的支护压力不均匀分布对于预测结果的重要性，并指出传统楔形体模型的局限性。

中文关键词： 隧道；变形；小应变刚度；桩；管线

英文摘要： Based on the latest laboratory research results on soil small strain stiffness, a constitutive model is proposed, which is capable of considering the different non-linear stiffness behavior under loading and unloading, especially the small strain stiffness. A simplified transverse-isotropic elastic homogenization model is also proposed for the pre-support of tunneling, while different numerical methods of simulating tunnel excavation are discussed. Three-dimensional numerical analysis has been carried out to study the soil deformation around shallow-buried metro tunnel excavation. Different construction sequences are compared, while the three-dimensional effects with different pre-support lengths and excavation lengths are investigated. The influence of tunneling on adjacent pile foundation at different locations is studied and the underlying mechanism is discussed. The analytical results are compared with those from field monitoring and laboratory model testing. The effect of tunneling on adjacent buried pipeline is also studied, with a number of factors being investigated, including the pipeline stiffness and depth, volume loss, soil stiffness and tunnel depth. Based on the results, a simplified method to calculate pipeline maximum bending moment is proposed for preliminary design. Finally, the face stability of very large slurry shield-driven tunnel in sand is investigated, which demonstrates the importance of considering the non-uniform supporting pressure distribution on the tunnel face due to the density of the slurry. The limitations of the conventional wedge method are also highlighted.

英文关键词： tunneling; deformation; small strain stiffness; pile; pipeline